The present invention relates to a flat type heat pipe which is small-sized, easy to produce, superior in heat conductivity, and adapted to cool heat generating electronic components such as Insulated Gate Bipolar Transistor (IGBT), Intelligent Power Module (IPM), power elements (transistor) of thyristors, or rectifying devices.
It is known to use roll bond panels as effective cooling means of electronic components relating to power electronics which are used for electronic equipment and power electric equipment.
The above-mentioned roll bond panels, as shown in FIGS. 23a and 23b, are produced by thermo-pressure-bonding and includes two aluminum plates 80, 81 and a release agent therebetween at a portion which forms a heat transferring path 25 wherein a portion of the release agent is inflated by air pressure. The roll bond panel is shaped in such a manner that a portion of the heat transferring path 25 protrudes, so that a surface of the roll bond panel is made concavoconvex.
The roll bond panel has the following problems:
(1) Because it is formed by inflating the portion of the heat transferring path 25 by air pressure, the dimensional accuracy of the heat transferring path 25 cannot be improved. Also, it is difficult to make the heat transferring path 25 thinner.
(2) Because the aluminum plates 80, 81 are thermo-pressure-bonded, grooves (narrow grooves) or wicks cannot be disposed thereon, thus the high heat conductivity cannot be obtained.
(3) Because the surfaces of the aluminum plates 80, 81 are concavoconvex, it is difficult to attach fins which are useful for improving the radioactivity to the surface of the aluminum plates.
It is therefore an object of the present invention to provide a flat type heat pipe, which has an optionally contoured heat transferring path with high accuracy, which is thin, which provides grooves and wicks, and which structure facilitates the attachment of the fins.
A first embodiment of the present invention provides a flat type heat pipe characterized in that at least two aluminum plates arranged substantially in parallel with each other are brazed to each other so as to form a heat transferring path therebetween, and an operating liquid is filled in the heat transferring path.
A second embodiment of the present invention provides a flat type heat pipe wherein an aluminum plate which is worked in a corrugated manner is interposed between two aluminum plates.
A third embodiment of the present invention provides a flat type heat pipe wherein the aluminum plate which is worked in the corrugated manner is an aluminum brazing sheet.
A fourth embodiment of the present invention provides a flat type heat pipe wherein penetrating holes are disposed on side walls of the aluminum plate which is worked in the corrugated manner.
A fifth embodiment of the present invention provides a flat type heat pipe wherein a metal tube is brazed onto an open end of the heat transferring path and a predetermined portion of aid metal tube is sealed by pressure bonding and/or welding.
A sixth embodiment of the present invention provides a flat type heat pipe wherein supporting bodies are arranged between the at least two aluminum plates which are substantially in parallel with each other, in such a manner that the aluminum plates are spaced at a predetermined distance.
A seventh embodiment of the present invention provides a flat type heat pipe wherein a predetermined number of protruding portions are formed on one aluminum plate of the at least two aluminum plates arranged substantially in parallel with each other and leading portions of the protruding portions are joined to the other aluminum plates.
An eighth embodiment of the present invention provides a flat type heat pipe wherein grooves are formed on inner surfaces of the heat transferring path, and/or a wick is arranged on the heat transferring path.
A ninth embodiment of the present invention provides a flat type heat pipe wherein the wick comprises grooves forms on an inner surface of the aluminum plate, or an uneven portion formed by melting a brazing filler material forms the inner surface of the aluminum plate, whereby the brazing filler material is solidified and forms the inner surface of the aluminum plate.
A tenth embodiment of the present invention provides a flat type heat pipe wherein the wick comprises a wave-like plate brazed onto the aluminum plate, a cylindrical wire netting, a plate-like wire netting, or a number of spheres adjacent to each other.
An eleventh embodiment of the present invention provides a flat type heat pipe wherein protruding portions are formed on one aluminum plate of the at least two aluminum plates arranged substantially in parallel with each other, hole portions are disposed on the other aluminum of the same, and the aluminum plates are positioned by inserting the protruding portions into the hole portions.
A twelfth embodiment of the present invention provides a flat type heat pipe wherein fins are brazed onto a part or the whole of the surface of the aluminum plate.
Further objects and advantages of the invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.